What is wrong with my rat?

It might be the type of bedding you are using for the rat. I've had certain problems like that where some rats get reactions from certain bedding. He's getting more cuddly just like how a child does when they are very ill. YOU MUST TAKE IT TO THE VET!!! Get him checked out, they will tell you what you will need to do. It might be something more then just the bedding, the sooner you take him the better. If he is having a hard time eating solid food try finding pellets that is right for all rodents and mix it with a little bit of water to make it easier on him. Good Luck! I hope he'll be ok.